Balanced valvular-throttle mechanism for pneumatic hammers



June 1 1926.

W. J. DEVLIN BALANCED VALVULAR THROTTLE MECHANISM FOR PNEUMATIC HAMMERS Filed August 1923 INVENTOR Patented June 1, 1926.

UNITED stars mum WILLIAM J. DEVLIN, OF PHILADELPHIA, PENNSYLVANIA.

BALANCED VALVULAE-THEOTTLE mucnanrsur roarnnuMArIc HAMMERS.

Application filed August 6, 1923. Serial No. 655,837.

My invention relates to a novel construction of a balanced valvular throttle mechanism for the grasping handle of a pneumatic hammer adapted for sealing, chipping, caulking riveting and other purposes, wherein I construct the valvular element in such a manner that the same is balanced under all conditions, whereby the operator of the hammer can control the initial opening and closing of the throttle valve in the handle with great nicety and exactness. so that the hammering piston will initially impact upon the work with light striking blows at starting so as to prevent the piston, in the case of riveting from driving the hand holder-on away from its proper position, when the pneumatic hammer begins to operate.

My invention is also applicable to chipping hammers, since it permits the operator to readily regulate the striking blows at starting, so as to take a very light chip, the

force of the blows being thereafter readily increased to the full capacity.

To the above ends my invention consists of a novel construction ofa balanced poppet valve, having an annular air channel, and upper and lower heads provided with vertical grooves whereby the valve becomes instantaneously balanced when slightly opened, thereby allowing the hammer to be prop- -erly regulated by starting light striking blows. which can be regulated up to the full capacity of the hammer, the operator being in full control of the hammer at all ti tries and in all positions, which is essential in pneumatic hammers of the character to which my'invention appertains.

It further consists of a novel construction It further consists of other novel featuresof construction and advantage. all of which will be hereinafter fully set forth and pointed out in the claims.

For the purpose of illustrating my invention, I have shown in the accompanying drawings one form thereof which is at present preferred by me, since thesame has been found in practice to give satisfactory and reliable results, although it is to be understood that the various, instrumentalities of which my invention consists can be variously arranged and organized and that my invention is not limited to the precise arrangement and organization of these instrumentalities as herein shown and described.

Figure 1. represents a vertical sectional view of the throttle valve mechanism for the handle of a pneumatic hammer, embodying my invention, the valve being in closed position. i Figure 2 represents a view similar to Figure 1, but showing the manually operated valve lever in the position it assumes when the throttle valve is opened or unseated.

Figure 3 represents on an enlarged scale, a side elevation of the valve bushing and its adjuncts.

Figure 4 represents a vertical section, on line- 4-4, Figure 3. Y

Figure 5 represents a side elevation of the plunger, valve, spring, and closure removed from their l'wu shing.

Figure 6 represents on an enlarged scale. a horizontal section on line 6-6, Figure 4;

Similar numerals of reference indicate corresponding parts.

Referring to the drawings In carryingout my invention I have shown the same as adapted to a long stroke rivetmg hammer, 1, seen in dotted lines, although my invention is equally adapted to scaling, chipping, and caulking hammers. These hammers are usually provided with pistol grip handles as 2, a conventional type of which is sh'own in Figures 1 and 2. 3 designates the inlet for the motive fluid, as compressed air, which isprovided with a screen 4 through which the air passes into the chamber 5, which is provided with the valve bushing 6. The valve bushing is provided with the lower head 7, and the intermediate head 8, which have adrive fit within the handle 2, the upper end of the-buslr ing engaging the upper portion of the handle. 9 designates inlet ports for the motive fluid, which flows into the chamber 10, which contains aspring 11, the lower end of which is seated in the cup 12 of the closure 13 having the nut 14:. The upper end of the spring engages the teat 15 of the poppet .valve 16, and bears against the underside 17 of said valve and normally forces the latter upwardly against itsseat 18, it being apparent that the upper beveled end 19of said valve is normally always pressed against said seat 18. The valve 16 has the central' groove or air channel 20, the upper head 21 and the lower head 22. The upper head has a series of vertical cuts or air channels 23, while the lower head 22 has a series of slots or air channels 24 therein, said slots being shown in the present instance as cut in vertical alignment, since they are preferably cut in one operation by the milling tool.

It will be seen from Figure 5, that the upper slots 23 merge into the beveled end 19, so that at the instant the valve 16 is unseated the pressure above and below the valve becomes substantially balanced, the motive fluid being admitted under the valve at all times, so that a. very slight pressure of the operators thumb, as will be hereafter explained, serves to regulate the opening of the valve at starting with great nicety and exactness.

In practice I have found the best results to be obtained by making the depth of the air channels 23, ten one thousandths of an inch, and the air channels 24, fifteen one thousandths of an inch deep. The depth of the main channel 20 is thirty two one thousandths of an inch and it is of an inch wide. The air channels 23 and 24: are of .an inch wide. The vertical height of the upper head 21 is of an inch, and of the lower head 22 is of an inch It will be evident that the above dimensions and proportions may be varied, but I have obtained the best results from the same.

The stem 25 which depends from the plunger 26 is normally always seated in the top of the valve 16 as seen in Figure 4, said stein being actuated by the cam member 26 of the lever 27, fulcrumed at 28 in the 29, positioned in the upper part of the handle 2, said lever being provided with a thumb piece 80. The upper end of the bushing 6 is provided with a slot 31 in which the lower end of the lever 27 functions as will be apparent in Figures 2 and 4.

Above the valveseat 18 is the air outlet chamber 82, from which the air has its exit through the ports 33 in the bushing 6, to the passage 34, leading to the vitals of the hammer 1.

The operation is as follows:

The parts normally appearas seen in Figures 1 and 4c, the spring 11 holding the valve 16 against its seat 18. IVhen the manually operated lever 27 is depressed from the position seen in Figure 1. into the position seen in Figure 2, the plunger 26 and its stem 25 are depressed, thereby moving the valve 16 downwardly and unseating the same. The instant the valve 16 is unseated, the pressure above and below the same becomes substantially balanced and the extent of the valve opening can be regulated with great nicety and exactness by a. slight pressure on the finger piece 30, thereby allowing the hammer to be properly regulated for light striking blows of the piston at start- 111g, which can be regulated from a gentle impact, up to the full capacity of the hammer, by a slight pressure on the finger piece 30, the operator being in full control of the hammer at all times and in all positions of the same.

My invention is especially useful in a riveter, since the 'riveter can be started slowly, so that the hammering piston will in starting strike light blows which will not drive the hand holder-on, away from its proper position, when the riveting operation is begun.

It is also useful in a chipping hammer since it enables the chipper to take a light chip at starting, and it is equally useful in stone working tools, as is evident. My invention can be readily applied to existing tools, as the bushing and its adjuncts can be inserted or removed as a unit, and as the number of moving parts is reduced to a minimum the device cannot readily get out of order, as is evident.

It will be understood that while I have shown my invention as applied to an open or pistol grip handle it is equally adapted for a closed pneumatic tool handle.

It will now be apparent that I have devised a novel and useful balanced valvular throttle mechanism for pneumatic hammers which embodies the features of advantage enumerated as desirable in the statement of the invention and the above description, and while I have, in the present instance, shown and described a preferred embodiment thereof which will give in practice satisfactory and reliable results, it is to be understooe that this embodiment is susceptible of modification in various particulars without departing from the spirit or scope of the invention or sacrificing any of its advantages.

Having thus described my invention,what I claim as new and desire to secure by Letters Patent, is 2- 1. In a device of the character stated, the combination of a pneumatic tool handle, a bushing therefor extending transversely through the major portion of said handle and having a valve seat therein, inlet and outlet ports below and above said seat respectively, an upwardly seating valve, in said bushing having the bevelled valvular portion 19, a spring for normally pressing said valvular element upwardly against said seat, upper and lower radially disposed air channels formed in said valve of different depths, said upper channels merging into said bevelled valvular portion, an intermediate main annular air channel between said upper and lower channels and in communication with the inlet ports of said bushing, whereby constant air pressure is admitted below said valve, a plunger and a pendant stem contacting with said valve, and means for actuating said plunger and valve in unison to unseat said valve.

2; In a device of the character stated, the combination of a pneumatic tool handle, a bushing extending transversely through the major portion of said handle and having lower and upper heads 7 and 8, and lower and upper ports 9 and 33 on opposite sides of said upper head, a valve seat Within said bushing located intermediately of said ports, an upwardly seating valve Within said bushing having a valvular element 19 provided with longitudinally extending ports merging thereinto, so that when said valve is unseated a minimum quantity of 15 motive fluid initially passes therethrough, a lower head on said valve having longitudinally extending ports therethrough, a spring below said valve for normally pressing the latter against its seat, means for adjusting the tension of said spring, a plunger occupying the upper portion of said valve bushing, a pendant stem on said plunger having its lower end engaging said valve, and

means for-manually actuating said plunger 2 and valve against the tension of said spring.

WILLIAM J. DEVLIN. 

